They edited the profanity, the nudity, and for the sake of fitting it into the time slot, a few conversations. They really didn't need to cut the violence, but there are some scenes where they only flash on it, rather than have the camera linger.
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Emotions associated with sex are harder for him to fake. Every time he sleeps with a woman, she sees something in him that freaks her out and she leaves him. Its safer for him to just avoid it.

In the first season he finds it "messy" and "human". He does not see himself as "human" as he is so different and fakes all feelings/emotions to fit in and not be seen for what he is. His life is "clean", his apartment is clean (he was uncomfortable with Debra's messiness when she stayed at his place), his crime scene is set up for as little mess as possible and he disposes of all debris to leave the area clean so as not to be detected. Eventually Dexter gets over his hangups and his sexual life begins to resemble the average male's.

Music from every season (from season 1 to season 6) can be found separately for purchase on Amazon.com. Each season has its own released official soundtrack (the soundtrack for seasons 2 and 3 were released together in the same disk) Music from season 7 will be released sometime in the future as well.
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You're in luck! Someone has. Television Without Pity has excellent detailed summaries that far outdo anything we could type here. You can click this link to get there. http://www.televisionwithoutpity.com/show/dexter/recaps
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Spoilers

He and his brother witnessed their mother murdered with a chainsaw in a cargo container as children. They were found days later in a pool of blood that was 2 inches deep. He was taken in by Harry Morgan, who saw him for what he was, a sociopath. Harry taught him a code of ethics that helped him to satiate his bloodlust successfully and also help rid his little section of the world of other serial killers who could escape the justice system. His brother was taken in by the state and was never trained the way Dexter was.
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Including his past kills, and the growth of his slide collection between seasons, Dexter has killed (at the very least) 100 people: around 55 of these have been on-screen kills (including flashbacks). In S5E1 he claims to have killed 67 deserving people, though if the 12 inbetween S3 and S4 is taken into account (portrayed in the Turned Upside Down promo), this should actually be around 88 at the start of season 5.

In S2E8 Dexter's slide box is revealed to have 46 slides in it. Taking into consideration all the on-screen slide kills from S1E1(including flashbacks) till then, there are 32 slides unaccounted for (though at least 18 are identified during the BHB investigation). It is established that Dexter has killed before he began to take trophies (First Nurse, Juan Rinez,), which brings Dexter's potential pre-series kill total to 36 (this includes Early Cuts characters Peter Thorton and Robert Milson).

Clint Mckay - Stabbed in the chest and thrown overboard - extorting Hannah and Dexter No blood taken

This kill is significant in that Clint doesn't really meet the code. Dexter rejects the Dark Passenger, realising he is in control of his killing, and decides to let a guilty victim go so he can focus on Clint: becoming a killer who kills because he wants to, not because he needs to.

In Season 1, Episode 9, Dexter learns that his biological father Joe Driscoll has passed away. He takes a blood sample from him and has Masuka run a paternity test comparing it to his own. The paternity test proves that Joe Driscoll is Dexter's biological father.

In Season 2, Episode 5 we learn that Dexter's adopted father Harry was engaged in an extramarital affair with Dexter's biological mother Laura Moser. However due to the paternity test in the first season, we know that there is no way Harry can be Dexter's biological father unless Joe Driscoll was related to Dexter some other way or the paternity test was wrong which are both highly unlikely.
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Only season 1 followed the main plot line of the first book. In season 2, the shows writers went their own direction, though they do appear to have adopted some elements from the other books, (The Skinner resembles Dearly Devoted Dexter's Dr Danco, as is the case for S2's Doakes sub-plot.)
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